Chelsea confirmed the deal on their official website, stating: "Everybody at Chelsea Football Club would like to thank Demba for his service and wish him all the best for the future."

Besiktas president Fikret Orman spoke of his delight with the club's new acquisition this week.

"Ba is a player we all believe in, we put in a lot of time and effort to complete the transfer to the best of our interests," Orman said. "The transfer is within our budget and we are delighted to have completed the move."